Wireless Local Area Networks (WLANs) have two basically operation modes: infrastructure and ad hoc wireless. In infrastructure mode, mobile nodes communicate with each other via an access point (AP). In ad hoc wireless mode, peer devices may communicate directly without going through an AP, that is, without a network infrastructure. As such, the ad hoc wireless mode is useful for establishing a network where a wireless infrastructure does not exist and an AP is not accessible.
WLANs are comprised of basic service sets (BSS), each BSS including of at least two stations (STAs) within each other's transmission range. A BSS in an ad hoc wireless network is also referred to as an Independent BSS (IBSS). Mobile stations within an ad hoc wireless network or IBBS may randomly or periodically enter or exit the ad hoc wireless network.
IEEE 802.11 provides guidelines for operating WLANs in ad hoc wireless mode. Since many stations in WLANs are portable and battery-operated (e.g. cellular phones, laptop computers, personal digital assistants (PDAs), wireless digital cameras, etc.), power consumption is a big concern and power saving is critically important in order to extend the operating life of the stations in the WLAN. Power may be best saved in wireless communication devices by switching them off.
The current IEEE 802.11 standard provides for a power save state that allows for one or more components of a wireless station to enter a low power, or “doze” state, for the portion of a beacon interval following the an announcement traffic indication message (ATIM) window. The wireless station may then be awoken at the start of the next beacon period as necessary to transmit and/or receive transmissions.
However, IEEE 802.11 currently provides that a station is only eligible to doze for a remainder of a beacon interval if certain conditions occur, that is, if the station has not transmitted a beacon signal, not received an ATIM management packet, and not transmitted ATIM management packets within a beacon period. The IEEE 802.11 standard does not currently allow a station to sleep at other times even though the station may not be needed or in use. Therefore, on many occasions, a station is unnecessarily awake (and consuming power) for the remainder of a beacon period.
Accordingly, it would be desirable to have additional methods and systems for minimizing power consumption by stations in an ad hoc wireless WLAN.